Color vision deficiency or color-blindness relates to a decreased ability to discriminate between colors. Generally, there are two major types of color blindness. For example, there are those who have difficulty distinguishing between red and green and those who have difficulty distinguishing between blue and yellow.
There are several causes for these types of color blindness to take place and there are several gradations of the deficiency. For example, persons may have difficulty distinguishing between two colors. Dichromacy is a color vision defect in which one of the three basic color mechanisms is absent or not functioning. For example, protanopia is a type of color vision deficiency caused by the complete absence of red retinal photoreceptors. Accordingly, for a person having protanopia red appears dark. Further, deuteranopia is a color vision deficiency, in which the green retinal photoreceptors are absent so that it cannot be discriminated between red and green. Tritanopia is a color vision deficiency, in which the blue retinal receptors lack. Further, there exists a further type of color vision deficiency called anomalous trichromacy, which occurs when one of the three cone pigments is altered in its spectral sensitivity. This results in an impairment, rather than loss, of trichromacy, i.e. the normal three-dimensional color vision.
Concepts in order to convert colored images for improving the color differentiation for color blind comprise—inter alia—methods in which first the kind and the degree of color vision deficiency of a specific person is assessed, and thereafter, a method that is tailored to the person is applied, for example, by applying different textures to different colors. Further methods comprise changing the position of specific colors in the corresponding color space, for example, the CIE Yu*v* color space in order to increase the difference between respective colors.
Related concepts are, for example, known from U.S. Pat. No. 7,394,468, US 2010/0134810, Chin-Lun Lai; Shu-Wen Chang, “An Image Processing based visual Compensation System for Vision Defects”, 2009, 5th International Conference on Intelligent Information Hiding and Multimedia Signal Processing, 12-14 Sep. 2009, and Yia-Bin Huang, Sih-Ying Wu, Chu-Song Chen, “Enhancing Color Representation for the Color Vision Impaired”, September 2008.